1. Field of the Invention
This invention relates, generally, to coin operated mechanisms and, more particularly, to a control arrangement for preventing rapid on-off cycling or flutter of the timer and mechanism being controlled, due to flutter or vibration in the leaf-spring control switch.
2. Description of the Prior Art
Coin operated mechanisms of the type commonly referred to as commercial applicances, such as clothes washers and dryers, are usually provided with rotary coin meters or coin slide assemblies which require the insertion of one or more coins to initiate the operating cycle of the mechanism. The length or duration of the operating cycle is controlled by an electrically operated timer which is part of the control device. Examples of such prior art control devices are disclosed in U.S. Pat. Nos. 2,915,692; 3,168,947; 3,172,520, 3,614,681, and 4,094,396.
In one form of such control device, a ratchet wheel and a star wheel are rotatably mounted on a common shaft. Each of said wheels carries an eccentrically mounted pin located at an equal radial distance from the axis of the shaft and has a series of equally spaced teeth with wells defined therebetween The pins project toward one another and are adapted to engage upon rotation of one wheel relative to the other. The ratchet wheel is driven or stepped by a pawl assembly which, in turn, is operatively associated with either a coin slide assembly or solenoid assembly. In either case, deposit of a proper coin in the device permits the coin slide or solenoid to operatively move the pawl assembly in a manner to stepwise rotate the ratchet wheel in one direction a distance of one tooth. Such rotation establishes an angular separation between the pins of the ratchet wheel and the star wheel. A spring biased arm having a ratchet follower portion is provided to operatively connect the ratchet wheel to a snap-action leaf spring switch. The operation is such that as the ratchet wheel rotates, the ratchet follower moves up a tooth front face to the tooth apex, and finally drops down the back tooth face into the next adjacent well. This carries the arm up and down which, in turn, normally effects movement of the switch to an open and closed state, respectively, stopping or initiating, respectively, the operating cycle of the mechanism. As the stepwise rotation of the ratchet wheel is so arranged as to always be completed with the ratchet follower disposed in a well, the switch is released to move to its closed state at the end of each stepping operation.
Movement of the switch to its closed state also serves to energize an electrically operated timer which, in turn, effects rotation of a pin wheel attached to the timing motor shaft. The coin operated mechanism load is simultaneously energized by the switch. Rotation of the pin wheel causes the pins thereof to engage with the teeth of the star wheel and intermittently rotate said star wheel in the same direction of rotation as the ratchet wheel. Rotation of the star wheel causes the pin therof to engage with the pin of the ratchet wheel. Continued rotation of the pin wheel effects conjoint rotation of the star wheel and the ratchet wheel in said one direction, due to the engagement of said pins. As the ratchet wheel rotates, the ratchet follower rides out of a valley and up the next adjacent ratchet tooth front face until the switch operating arm is displaced to a position to effect movement of the switch to its open state. This switches off the power supply to de-energize the timer and the load, and terminates the operating cycle of the mechanism.
In the device as described above, it is possible for the star wheel to counterrotate in a direction opposite to said one direction when the switch is in its open state and permit the ratchet sheel to similarly counterrotate in said opposite direction under the influence of the spring biased switch arm. Such counterrotation of the ratchet wheel permits the ratchet follower to drop back into a well between adjacent teeth thereby effecting movement of the switch to its closed state and activating the timer and mechanism. This, again, causes the pin wheel to rotate ever so slightly causing conjoint rotation of the star wheel and ratchet wheel until the ratchet follower is again displaced out of the well and up the front face of the next adjacent tooth to effect movement of the switch to its open state.
Restraining means, such as disclosed in U.S. Pat. Nos. 2,915,692 and 4,094,396, are intended to prevent or reduce the likelihood of such counterrotation of the ratchet wheel after the mechanism has completed an operating cycle. However, it has been found that these star wheel/ratchet wheel type of mechanisms still can rapidly cycle on and off, possibly burning-out the swithces and motors controlled by the device. Apparently, this is caused by the snap-action leaf spring control switch which, while supposedly in its off position, is nonetheless capable of fluttering rapidly between its on and off positions thereby switching the device timer motor and load rapidly on and off.
More specifically, the switch is of the kind that is referred to as being "normally closed." That is, the circuit is activated when the switch button is released to its closed position. As described above, when the ratchet follower has ridden high enough on the front face of a ratchet tooth, due to conjoint rotation of the star wheel and the-ratchet wheel, the switch is displaced inwardly to separate slightly the switch contacts whereupon the power to the timer motor and the load is disconnected. Because the timer mechanism operates slowly, stopping the timer motor stops the opening of the switch contacts with the switch left in this somewhat unstable condition with the contacts suspended in very close proximity to each other. In other words, slight separation of the switch contacts deactivates the timer motor before the switch snaps to its positive "off" or "open" state. This results in a situation wherein very little pressure is necessary to close the contacts and a small vibration can cause the contacts to touch to reactivate the timer mechanism. The cycle can thus become a rapid self-sustaining flutter since the switch has not yet snapped to tis positive open state.
It is therefore an object of this invention to ensure positive "off" switching to prevent damaging flutter in the control device.